Quick-break disconnect switch



Ap 20, 1943. w. o. SCHULTZ ETAL QUICK-BREAK DISCONNEC'I' SWITCH FiledJune 16, 1959 4 Shets-Sheet 2 Patented Apr. 20, 1943 Line MaterialCompany,

QUICK-BREAK DISCONNECT SWITCH William C. Schultz, South Milwaukee, andAlwin G. Steinmayer, Milwaukee, Wis., assignors to South Milwaukee,

Wis., a corporation of Delaware Application June 16, 1939, Serial No.279,414

16 Claims.

This invention relates to quick-break disconnect switches.

In electrical distribution circuits operating on comparatively highvoltages and amperages, it is customary to provide a manually-operableswitch for sectionalizing and interconnecting distribution feeder lines.When these switches are opened under load and where no provisions aremade for obtaining instant wide separation of contacts, arcing which isdestructive to the contacts occurs between the contacts.

Various provisions have heretofore been made in disconnect switches forobtaining quick, wide separation of switch contacts, but is has beenfound that the speed of separation and the arrangement of the parts havepermitted some arcing-between the separating contacts with the resultthat such contacts are frequently damaged.

Therefore, it is the principal object of this invention to provide for adisconnect switch, an auxiliary switch which will maintainclosed-circuit conditions until the disconnect switch has openedsufficiently to avoid arcing between its contacts and which willthereafter break the circuit in a minimum interval of time without anyarcing to the contacts of the disconnect switch.

More specifically, it is an object to provide for disconnect switches,an auxiliary switch including an inherently resilient switch memberadapted to be flexed when the disconnect switch is moving to openposition, thereby biasing the switch member to open position and to bereleased for such movement during movement of the disconnect switchafter the circuit there through is opened.

Another object is to provide improved camaction means facilitatingoperation of the disconnect switch to open-circuit position. Thisfeature is the subject matter of our divisional application, Serial No.337,194, filed May 25, 1940.

A further object is to provide full-floating and self-aligning contactsadapted to insure efficient and smooth operation of the switch. Thisfeature is also the subject matter of the above identified divisionalapplication.

In the drawings:

Fig. 1 is a view in side elevation, partly in section, showing a houseddisconnect switch embodying this invention.

Fig. 2 is a view similar to Fig, 1 showing the switch moved toward openposition.

Fig. 3 is a view in front elevation with the housing door substantiallyremoved.

Fig. 4 is a sectional View taken on the line 4-4 of Fig. 1.

Fig. 5 is a detail view of a part of the switch structure.

Fig. 6 is a front view of the switch housing with the door removed and afragmentary part of the switch in open position.

Fig. '7 is a front view of a fragmentary portion of the housing with theswitch in open position.

Like parts are identified by the same reference characters throughoutthe several views.

The housing for the switch comprises insulating material, such as wetprocess porcelain, which is moulded to form a relatively thick rear wallI, a top wall 2, side walls 3, and bottom wall 4 having a recess 5.

A door 6, made of insulating material such as Bakelite, is pivotallymounted at its upper end adjacent the top wall 2 within the recessedportion 1. The pivot for th door may comprise a pin 8 extending throughthe walls 3 and the hub portion 9 on the door. Disposed on the pin 8, ateach end of the hub portion 9, are a resilient friction plate It andpressure member H coacting to resist pivotal movement of the door andthus providing means for retaining the door in open position extendinghorizontally from the housing as indicated in Fig. 2. The means forretaining the door in elevated position has not been shown in greatdetail, since any suitable means may be provided for obtaining theintended result. I The rear wall I of the housing is provided withspaced terminal supports and I6 anchored in the recesses I! by means ofcement or other desirable material [8 and with a pivot plate or blade l9spaced from the support 16 and anchored in the recess 20 by means ofcement 2i. Secured tothe outer face of the rear wall I by any desirablmeans, such as bolts 22 anchored in the wall, is a pivot plate 23 havingits ends 24 bent angularly to coact with similar ends on the mountingstrap 25. The correspondingencls of the plate 23 and strap 25 arepivotally connected by means of bolts 26 and are normally held againstrelative pivotal movement by means of the nuts 21. The strap 25 isprovided with bolts 28 cooperating with other parts, not shown forattaching the housing to a crossarm, not shown. Disposed between theterminal supports l5 and I6, is a barrier 29 which increases the leakagedistance between the supports.

The side walls 3 of the housing are each provided with spaced holes 30adjacent the terminal members 3| and 32 for the insertion of line wires,not shown, to be connected with the terminals in the manner hereaftermore fully disclosed. Each of the holes 30 is provided with a hood 33 onthe outer face of the respective walls 3 adapted to prevent rain andsleet from entering the housmg.

The terminal members 3| and 32 are identical and, as may be clearly seenin Figs. 2 and'G, each comprises a base 34 having a contact plate orblade 35 normal thereto and extending along a central portion thereof,Wing portions 36 at opposite'sides of the plate 35 and each having anaperture 31, clamping jaws 38 disposed on opposite sides of the plate 35and spaced. from adjacent wing portions 35, and spaced legs39. Asimay beclearly seen in Figs. 2 and 6, the contact plate 35 is L-shaped toprovide a narrower portion 4|] which serves as a camming surface morefully described hereafter.

The terminal members 3|. and- 32 are loosely mounted on the terminalsupports [5 and I6, respectively, to obtain a full-fioatingjeiiectpermitting lateral and angular alignment thereof.

relative to the supports and with the. switch.

blades subsequently more fully described. This mounting is secured bymeans of the sleeves. 4| which fit loosely in the apertures 31 in theterminal members. The sleeves are rigidly retained on the supports andI6 by means of bolts 42 which extend through the sleevesand are threadedinto the supports.

The upper terminal member 31 is retained" on the sleeves by means ofauxiliary L-shapedjcontacts 43 in which the bases 44 serve as washersconfined between the sleeves 4| and the heads of the bolts 42. Thelength of the. sleeves 4| is greater than the distance between the baseofthe legs 39 andfa'ce of the wing portions 35. on terminal member 3!,thereby permitting movement of the member between the contact bases 44and the support I5. The outer ends of the L-shaped contacts 43 are eachprovided with a deflection or wedge-like portion 45 which terminates ina rearwardly-extendinghook 46, more fully disclosed in Fig. 4. V

The lower terminal member 32 is secured'to the support It in a similarmanner withthe exception that a washer 4'! replaces the base 44 on theL.-shaped contact 43. Disposed betweentheterminal members 3| and 32 andthe supports l5 and I6 are plate springs 48, shown in detail in Fig. 5,which serve to hold the'members outwardly of the supports and in contactwith the bases 44 and washers 41, respectively.

Mounted on each of the. clamping. jaws 38 is a movableclamp having anelongated opening 5i receiving the jaw 38 andprovidedwith aclampactuating bolt 52 extending into and lengthwise of the opening 51for actuating engagement with the jaw 38. The bared ends of conductors,not shown, may be passed through the holes 30 in the sides 3 of thehousing and inserted between the cooperative clamping surfaceson thejaws 38 and clamps 50 and clamped thereby upon appropriate manipulationof the bolts 52.

The switch blade comprises a pair of spaced, parallel, flat bars 53 and54 which are pivotally mounted at the lower end of the housing on, thepivot bolt 55 which extends through the bars 53 and 54 and the pivotplate is and is secured in such position by means of the nut 56 and:lock nut 57. The upper ends of thebars53 and 54, as viewed in Figs. 1, 2and 3', or the lower end, as viewed in Fig. 7, are connectedby a bolt 59which extends through the bars and is held in position by means of a nut60. Preferably, the nut 60 is secured in' position by mutilating thethreads on the bolt, and cupped washers Bl are provided to give a degreeof resiliency and for maintaining the bars in firm frictional engagementwiththe contact 35 on upper terminal member-3|.

The upperportion of the bars 53 and 54x intermediate theenols thereof isprovidedv with abolt 62- which. extends through the bars andis securedin position by means of. a nut 63. This bolt in Fig. 1 is positionedbelow contact 35'on the upper terminal 3| and serves with the cuppedwashers 64 to hold the bars in firm contact with the contact 35.

Below the bolt 62, as viewed in Figs. 1 through 3 and above the contact35 on the lower terminal member 32, is a bolt 65 which extends throughthe bars 53 and. 54. Mounted on this bolt are a pair of tubesfifi, apairof cupped washers 61 and a pair oflstandard. washers 68. A nut 69retains the bolt 65 in position. This bolt also serves to hold the barsin firm frictional engagement with the contact 35 on the lower terminalmember 32.

Pivotallymounted on the bolt 65 and between the-bars53 and 54, isswitch-operating lever 10 of the first class having at its upper end apull-push ring 'H extending from between the bars, a cam finger l2, andstop finger 13 engageable with the pin 14 which extends through the bars53' and 54 and'is retained-in position by means of a washer 15and'cotter pin 16. V

A coil spring 18 positioned between the bars; 53' and 54 is engaged-atone end with the pin 14' and atthe-other end with the aperturedlug'lfl'on' the lever 10. lever 15 in the position shown in Figs. 1 and2 and against the bolt 62.

When it is desired to'move the switch from the closed position shown inFig. 1, the door 6, which is provided with a recess BA forreceiving thepull ring H, will be first moved to the position indicated in Fig. 2".Then the pull ring H onthe lever 10 will be engaged by asuitableoperatlng stick, not shown, and thereby pulled from. between thebars 53 and 54. As the lever 10 is pulled in the manner indicated, thecam finger 12 at'the lower end thereof will engage theportion 40 on thelower terminal member 32; Pressure thus applied to the member 32 willfirst cause the-member'to'assume substantially the position shown inFig. 2, and therafter cause' the switch blade to move outwardly aboutthe pivot bolt. to the position shown in Fig. 2 where the switch is outof contact with the contact 35 on the upper terminal member 3i. When theswitch has reached substantially the position shown in Fig. 2, thestopfinger 13 on the lever 10 will engage the pin; 14 and thereafter theswitch will be moved directly by means of the lever'to' the positionindicated in Fig. 7 whereit will be insulated from the terminal members3| and32.

In order to maintain the circuitfor a predetermined period of time whilethe switch is being moved from the position indicated in Fig. 2 to theposition shown in Fig. 7, resilient spring wire contacts are provided.When the switch is in closed position, the upper ends of the spring wirecontacts are in contact with the L-shaped contacts 43 at the upper endof the housing and are positioned as indicated in Fig. 4 within thebights of hooks 46.

The lower ends of the wire contacts 80 are each loosely coiled at 8|about a tube on the bolt 65 and extended therefrom to the pin 14 wherethey are anchored by hooked. portions 82. Intermediate the ends of thewire contacts 80, are guide plates 83 secured to the bars 53jand 54.Each of these plates is L-shaped and has the horizontal portion providedwith an elongated slot 84 through which the corresponding wire contact80 extends.

When the switch is in the positionsh'own in Fig. l, the wire contacts 80normally rest against the outer end of the slot 84 as maybe seen inFig. 1. Adjacent the upper end of each of the wire contacts 80 and belowthe L-shapedcon- This spring normally maintains" the" tacts 43, is astop plate 85 secured in any suitable manner, such as riveting, to oneof the bars 53 and 54. These stop plates serve to limit the movement ofthe wire contacts 80 relative to the switch after the wire contacts havedisengaged from the contacts 43 as will more fully appear hereafter.

Operation of the switch bars 53 and 54 from closed to open position hasbeen previously described. In Fig. 2, the switch bars are shown in aposition just after they have been disconnected from the upper terminalmember 3!. In this position, the wire contacts 80 are still inengagement with the L-shaped contacts 43 and consequently the circuit isstill closed. As the switch bars 53 and 54 move further from theterminal member 3|, the wire contacts 80 will be flexed until the upperends pass beneath the wedgelike portions 45 on the L-shaped contacts 43and are released for unobstructed movement toward the stop plates 85,whereupon the wire contacts will assume the position relative to theswitch bars 53 and 54 shown in Fig. 1.

In a circuit which is opened under load in the manner described, an arcmay be drawn between the upper ends of the wire contacts 80 and theL-shaped contacts 43 when the wire contacts leave the contacts 43.However, the duration of the arc will be very short because of the rapidmovement of the wire contacts away from the contacts 43 and suchcontacts will not be appreciably damaged.

It will also be noted that by drawing the are between the wire contactsand the contacts 43, the main parts of the switch, such as the bars 53and 54 and the contact 35 on the upper terminal 3|, will not besubjected to destructive arcs which might cause pitting of the mainportions of the switch.

As switch bars 53 and 54 are moved to closed position the upper endportions of contact wires 80 engage the angular cam surfaces on thewedge-like portions 45 of hooks 46 and are thereby caused to flexlaterally of the plane of movement of said bars until they clear thetips of the hooks, whereupon they snap back into the bights of therespective hooks and finally occupy approximately the position in whichthey are shown in Fig. 4.

As previously noted, the terminal members 31 and 32 are in effectfloating on the terminal supports I5 and 16, respectively. lhis permitsthe members 3| and32 to assume various positions during closing andopening movements of the switch bars 53 and 54 and thereby affordseflicient and smooth operation of the switch.

When the switch is in the open position shown in Fig. '7, the door 6 maybe closed to prevent accidental contact with the live portions in thehousing and to prevent small birds from attempting to rest on suchportions.

From the foregoing description, it will be obvious that a disconnectswitch has been provided in which arcing between the main portions ofthe switch has been eliminated and pitting thereof avoided when theswitch is opened under load, in which a maximum mechanical advantage isavailable for manual operation of the switch during movement of theswitch blade to its initial disconnect position, and in which a maximumefliciency and smoothness of operation of the switch is obtainable.

We claim:

1, In a quick-break disconnect switch the combination with a main switchcomprising a pair of spaced terminals and a pivotally-mounted switch barconnecting said terminals, of an auxiliary switch electricallyconnecting said terminals and including a catch associated with one ofsaid terminals and a resilient member engageable at one end with saidcatch and secured at the other end on said bar, said member comprising awire having a coiled portion intermediate its ends and relatively incloser proximity to the last-mentioned end than the other, and a pin onsaid bar about which said portion is coiled, said catch comprising ahook-like wedge portion normal to the plane of movement of said bar,whereby upon movement of said bar to open position said memher will bewithdrawn from said catch subsequent to the opening of a circuit throughsaid bar.

2. In a quick-break disconnect switch the combination with a main switchcomprising a pair of spaced terminals and a pivotally-mounted switch barconnecting said terminals, of an auxiliary switch electricallyconnecting said terminals and including a catch associated with one ofsaid terminals, a resilient wire contact engageable at one end with saidcatch and secured at the other end on said bar, said wire having acoiled por tion intermediate its ends and relatively in closer proximityto the last-mentioned end than the other, and means on said switch barholding said coil in a substantially fixed position relative to saidbar, said catch comprising a hook-like wedge portion normal to the planeof movement of said bar.

3. In a quick-break disconnect switch the combination with a pair ofspaced terminals and a pivotally-mounted switch bar frictionallyengaging said terminals, of a pivot pin carried by said bar, abar-actuating member for actuating said bar to open-circuit position,and aresilient wire having one end releasably latched with one of saidterminals and its other end anchored on said bar, said wire having aportion loosely coiled about said pin, said one of said terminalsincluding a latch adapted to flex said wire laterally of the plane ofmovement of said bar in one direction of movement thereof and to flex'said wire in a plane paralleling the plane of movement of said bar inthe direction opposite to said one direction.

4. In a disconnect switch the combination with a support having a pairof spaced terminal supports and a pivot in insulated relation thereto,of a pair of terminals each loosely mounted on one of said terminalsupports for lateral and angular movement thereon, a switch barfrictionally engaging said terminals and pivotally mounted on saidpivot, a bar-operating member for actuating said switch bar towardopen-circuit position, and a resilient wire electrically connecting saidterminals and releasably'latched at its upper end, the'other end of saidwire being anchored on said bar, the terminal adjacent said upper endincluding a latch adapted to flex said wire laterally of the plane ofmovement of said bar in one direction of movement thereof and to flexsaid wire in a plane paralleling the plane of movement of said bar inthe direction opposite to said one direction.

5. In a disconnect switch the combination with an insulating support, apair of terminals carried by said support in insnlatedrel'ation, a pivotcarried by said support in insulated relation to said terminals, aswitch bar pivotally mounted on said pivot and frictionally' engagingsaid terminals, a pivot pin carried by said bar, and a bar-operatingmeans foractuating said bar to open-circuit position, and a resilientmember having one end riele'a s'ab'ly latched with one ofsaid terminalsand secured at the other end on saidpivot pin, said one of saidterminals including a latch adapted to flex said wire laterally'of theplane of move= ment of said her in one direction of movement thereof andto flex said wire in a plane paralleling the plane of movement of saidbar in the direction opposite to said one direction, wherebyuponmovement of said bar to open position said member will be withdrawnfrom the last-mentioned terminal subsequent to the opening of a circuitthrough said bar.

6. In a disconnect switch the combination with an insulating support, apair of terminals carried by said support, a switch bar pivotallymounted on said support, and a pivot pin carried by said bar,abar-operating means supported by said pivot pin for actuating said barto open circuit position, of an auxiliary switch electrically connectingsaid terminals and including a catch associated with one of saidterminals, a resilient wire contact having a coiled portion intermediateits ends slidably engaged with said pivot pin and in contact at theother end with said catch, said catch comprising a hook-like wedgeportion adapted to move said wire laterally of said bar in one directionof movement thereof and in parallel relation to the bar in the otherdirection of movement thereof, whereby upon movement of said bar to openposition said member will be withdrawn from said catch subsequent to theopening of a circuit through said bar,

'7. In a disconnect switch including an insulating support, a pair ofterminals carried by said support in insulated relation and eachincluding a blade-like contact, a pivot support carried by saidinsulating support in insulated relation to said terminals and includinga blade-like portion,

and a pair of substantially parallel fiat bars 'frictionallyengagingsaid contacts and said portion and pivotally mounted on saidportion, the combination with said switch, of an operating lever mountedon said bars, an auxiliary switch electrically connecting said terminalsduring a portion of the movement of said bars to open positions, andmeans inter-engaging said auxiliary switch and bars for withdrawing saidauxiliary switch from circuit-closing position following'the opening ofthe circuit through said bars, said auxiliary switch comprising a pairof resilient wires each secured at one end to one of said bars andhaving its other end releasably held in electrical connection with oneof said terminals, said one of said terminals including latching meansadapted to flex said wires laterally of the plane of movement in onedirection of movement thereof and to flex said wires in a planeparalleling the plane of movement of said bar in the opposite direction,whereby said wires will be flexed during movement of said bars to openposition.

8. In a disconnect switch the combination with an insulating support, apair of terminals carried by said support in insulated relation, aswitch blade pivotally mounted on said support for engagement with saidterminals, a blade-operating means for actuating said blade toopen-circuit position, of a resilient wire contact carried by said bladeand operable thereby, and a latching means associated with one of saidterminals for said contact, said means including a deflection portionand a contact seat disposed in a plane normal to a plane including saidwire contact, said wire contact being movable laterally relative to saidmain blade by means of said deflection portioniinto saidiconta'ctseatsubsequent to the closing of the circuit by said blade through saidterminals, and withdrawn from said seat and circuit-closing position ina direction substantially normal to its lateral direction of closingmovement subsequent to the withdrawal of said blade from one of saidterminals.

9. The combination in a disconnect switch of a terminal, a main switchblade and an inherently resilient auxiliary switch blade, both saidblades being operable to engage and disengage said terminal, saidauxiliary blade being mechanically connected with said main blade andmovable in response to opening and closing movements of said main blade,latching means operative to retain said auxiliary blade in electricalconnection with said terminal during a predetermined initial portion ofeach opening movement of said main blade and further operative abruptlyto release said auxiliary blade and thus abruptly break said connectionwhen said main blade has completed each aforementioned predeterminedinitial portion of an opening movement, said latching means having adeflector port" n enga'geable by said auxiliary blade and operative toflex said auxiliary blade laterally of its normal plane of movementduring each closing movement thereof, whereby to effect a latchingengagement between said latching means and said auxiliary blade, saidlatching means being operative to release said auxiliary blade inresponse to an opening movement of said main blade without substantiallyflexing said auxiliary blade laterally of its normal plane of movement.

10. The combination in a disconnect switch of a terminal, a main switchblade and an auxiliary switch blade resilient in all directions lateralto its longitudinal axis, both said blades'being oper able to engage anddisengage said terminal, said auxiliary blade being mechanicallyconnected with said main blade and movable in response to opening andclosing movements of said main blade, latching means operative to retainsaid auxiliary blade in electrical connection with said terminal duringa predetermined initial. portion of each opening movement of said mainblade, and further operative abruptly to release said auxiliary bladeand thus abruptly break said con nection when said main blade hascompleted each aforementioned predetermined initial portion or anopening movement, said latching means hay-- ing a deflector portionengageable by'said auxiliary blade and operative to flex said auxiliarylade laterally of its normal plane of movement during each closingmovement thereof whereby to effect a latching engagement between saidlatching means and said auxiliary blade, said latching means beingoperative to release said auxiliary blade in response to an openingmovement of said main blade without substantially flexing said auxiliaryblade laterally of its normal plane of movement. I 11. The combinationin a disconnect switch of a terminal, a main switch blade pivoted at apoint remote from said terminal and operative to make and break contactwith said terminal, an auxiliary blade having a free end operative tomake and break contact with said terminal, said auxiliary blade beingoperable by and coincidentally with the operation of said main blade,said auxiliary blade being supported at a point remote from saidterminal and having a looped portion adjacent its point of support, saidlooped portion being operative to render said auxiliary bladesusceptible-of being readily flexed, at least in the plane of movementof said main blade about its pivot, and a latch operative to engage andretain the free end of said auxiliary blade in contact with saidterminal during a predetermined initial portion of each switch-openingmovement of said main blade, thereby causing said auxiliary blade toflex and thus store up energy within itself for effecting an abruptbreak of contact with said terminal, said latch being operative torelease said auxiliary blade in conse quence of a predetermined degreeof flexing thereof in the manner previously recited, the arrangementbeing distinguished in that said auxiliary blade abruptly breaks contactwith said terminal only after said main blade has broken contacttherewith.

12. The combination in a disconnect switch of a terminal, a main switchblade pivoted at a point remote from said terminal and operative to makeand break contact with said terminal, an auxiliary blade carried by saidmain blade and having a free end operative to make and break contactwith said terminal, said auxiliary blade being operable by andcoincidentally with the operation of said main blade and attached tosaid main blade at a point remote from said terminal, said auxiliaryblade having a looped portion remote from its free end and adjacent itspoint of attachment to said main blade, said looped portion beingoperative to render said auxiliary blade susceptible of being readilyflexed, at least in the plane of movement of said main blade about itspivot, and a latch operative to engage and retain the free end of saidauxiliary blade in contact with said terminal during a predeterminedinitial portion of each switch-opening movement of said main blade,thereby causing said auxiliary blade to flex and thus store up energywithin itself for effecting an abrupt break of contact with saidterminal, said latch being operative to release said auxiliary blade inconsequence of a predetermined degree of flexing thereof in the mannerpreviously recited, the ar rangement being distinguished in that saidauxiliary blade abruptly breaks contact with said terminal only aftersaid main blade has broken contact therewith.

13. The combination in a disconnect switch of a terminal, a main switchblade pivoted at a point remote from said terminal and operative to makeand break contact with said terminal, an auxiliary blade consisting of awire and having a free end operative to make and break contact with saidterminal, said auxiliary blade being operable by and coincidentally withthe operation of said main blade, said auxiliary blade being supportedat a point remote from said terminal and having a looped portionadjacent its point of support, said looped portion being operative torender said auxiliary blade susceptible of being readily flexed at leastin the plane of movement of said main blade about its pivot, and a latchoperative to engage and retain the free end of said auxiliary blade incontact with said terminal during a predetermined initial portion ofeach switch-opening movement of said main blade, thereby causing saidauxiliary blade to flex and thus store up energy within itself forefiecting an abrupt break of contact with said terminal, said latchbeing operative to release said auxiliary blade in consequence of apredetermined degree of flexing thereof in the manner previouslyrecited, the arrangement being distinguished in that said auxiliaryblade abruptly breaks contact with said terminal only after said mainblade has broken contact therewith.

14. The combination in a disconnect switch of a terminal, a main switchblade pivoted at a point remote from said terminal and operative to makeand break contact with said terminal, an auxiliary blade carried by saidmain blade and consisting of a wire having a free end operative to makeand break contact with said terminal, said auxiliary blade beingoperable by and coincidentally with the operation of said main blade andattached to said main blade at a point remote from said terminal, saidauxiliary blade having a looped portion remote from its free end andadjacent its point of attachment to said main blade, said looped portionbeing operative to render said auxiliary blade susceptible of beingreadily flexed at least in the plane of movement of said main bladeabout its pivot, and a latch operative to engage and retain the free endof said auxiliary blade in contact with said terminal during apredetermined initial portion of each switch-opening movement of saidmain blade, thereby causing said auxiliary blade to flex and thus storeenergy within itself for effecting an abrupt break of contact with saidterminal, said latch being operative to release said auxiliary blade inconsequence of a predetermined degree of flexing thereof in the mannerpreviously recited, the arrangement being distinguished in that saidauxiliary blade abruptly breaks contact with said terminal only aftersaid main blade has broken contact therewith.

15. A switch comprising a first and a second stationary contact, a mainswitch blade pivotally mounted on said first stationary contact andmovable into and out of engagement with said second stationary contact,a flexible auxiliary switch blade structure rigidly secured to said mainswitch blade and having a free end portion, latch means forming aportion of said second stationary contact for engaging and latching thefree end portion of said auxiliary switch blade structure during closingof said switch, said latch means resisting outward motion of saidauxiliary switch blade structure during opening movement of said mainswitch blade, said auxiliary switch blade structure flexing duringopening movement of said main switch blade and withdrawing its endportion from said latch means solely by relative sliding motion due toflexing of said auxiliary switch blade structure.

16. A switch comprising a first and a second stationary contact, a mainswitch blade pivotally mounted on said first stationary contact andmovable into and out of engagement with said second stationary contact,a flexible auxiliary switch blade structure rigidly secured to said mainswitch blade and having a free end portion, said auxiliary switch bladestructure being composed of wire, latch means forming a portion of saidsecond stationary contact for engaging and latching the free end portionof said auxiliary switch blade structure during closing of said switch,said latch means resisting outward motion of said auxiliary switch bladestructure during opening movement of said main switch blade, saidauxiliary switch blade structure flexing during opening movement of saidmain switch blade and withdrawing its end portion from said latch meanssolely by relative sliding motion due to flexing of said auxiliaryswitch blade structure.

WILLIAM O. SCHULTZ. ALWIN G. STEINMAYER.

